固井水泥石是脆性材料，井下易脆性破坏而影响油气开采，因此开展了竹纤维增韧水泥石研究.用NaOH 溶液对竹纤维表面改性；考察改性竹纤维对水泥石力学性能的影响；用红外分析、热重分析和微观形貌分析竹纤维的亲水性和分散性改善原因；对掺入改性竹纤维前后水泥石进行微观形貌对比，探讨其增韧机理.结果发现，(1)10％ NaOH 溶液处理24 h后，微观形貌观察(SEM)可知改性后竹纤维表面胶质被除去，极性降低，其亲水性和分散性得到改善；(2)掺入0．5％改性竹纤维后水泥石折压比提高100％，弹性模量降低31％，明显增韧；(3)竹纤维增韧水泥石的机理在于改性后竹纤维与水泥基体粘结强度提高，纤维在水泥石晶体间起“搭桥”作用，纤维与水泥水化物之间紧密粘结起“拉筋”作用.%Due to the cement was a kind of brittle material,brittle failure,which can both lead to the failure of well integrity and affect the exploitation,often occurs in the downhole.This paper studies about the influence of the bamboo fiber on the mechanical properties of cement for toughening the cement.Firstly,in this experiment, surface treatment by sodium hydroxide solution was used for bamboo fiber.Secondly,the influence of the modi-fied bamboo fiber on the mechanical properties of cement was investigated.Next,it has analyzed the reasons the hydrophilicity and the dispersity of bamboo fiber improved by making IR,TG and SEM tests.In the end,this experiment has explored the toughening mechanism by comparing the micro-morphology of cement with modi-fied bamboo fiber to the cement with unmodified one.The results of SEM reveals that the modified bamboo fi-ber surface glue was removed and its polarity decreased as well as the stickiness and dispersion improved after been soaked in the concentration 10% sodium hydroxide solution for 24 h.The cement joined 0.5% bamboo fi-ber has been toughened obviously with its ratio of bending-compressive strength increased 100% and the elastic-ity modulus decreased 3 1% compared to the blank samples.And the toughening mechanism of bamboo fiber ce-ment was due to the cohesiveness between the fiber and cement improved.The fiber plays a role of “bridge”in cement crystals,and it closes bond between fiber and cement like “brace”.
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